change the structure of the title page by using CSS

[ytyyutianyun]

I would appreciate assistance in customizing the structure of the title page in Jellyfin using CSS. Specifically, I intend to adjust the layout and enlarge the thumbnail to match the screen size. To illustrate, I want to display the thumbnail within a photo element and position it on top of a section of the webpage, making its width equal to the screen or webpage width.
Could you kindly provide step-by-step instructions on how to achieve this customization? I appreciate your guidance. Thank you very much.